BIO 1000 Notes
Chapter 2.1 Notes:
Cell Theory(Notion of common descent) Ex: Kids from fertilized egg(common descent = egg)
• All organisms are composed of one or more cells.
• The cell is the basic structure and functional unit of all living organisms
• Cells arise only from the division of pre-existing cells.
• Bacteria, archaea, some protists(amoebas), some fungi(yeast) = UNICELLULAR(each
cell functionally independent organisms)
• Plants & animals = complex MULTICELLULAR(If cells broken= cant reproduce, grow)
• All forms of life grouped into 3 domains = Bacteria, the Archaea, the Eukarya. NOTE:
bacteria & archaea originally grouped into single domain: Prokaryota(prokaryotes)
• Smallest bacteria have diameter of 0.5 µm(micrometer). Chicken yolk = 1cm(0.1m)
Plasma Membrane: Bilayer made of lipids with embedded protein molecules(cells bounded by
this). Function = Separate/protect content of cell from external environment. TRANSPORT
materials into & out of cell.
Phospholipid Bilayer: Hydrophobic(non-polar/can’t mix with water) barrier to the passage of
water-soluble substances. BUT selected water-soluble substances can penetrate cell
membrane through transport protein channels. Arrangement = phospholipids two molec thick
• Selective movement of ions & water-soluble molecules through TP maintain ionic & mol
• DNA contains hereditary info(which is organized in the form of genes-segments of DNA
that code for individual proteins.
• Phospholipid molecule = Hydrophilic Head(phosphate) & two fatty acid hydrophobic
Cytoplasm: Contains the organelles the cytosol & cytoskeleton. (Interior of cell)
• All parts of cell between plasma membrane & central region MAKE UP IT
• Vital cell activities occur here = synthesis & assembly of molec required for growth &
repro(except those made in central region) & conversion of chemical & light energy into forms
that can be used by cells.
• ALSO conducts stimulatory signals from outside into cell interior
Organelles: Small organized structures important for cell function.
Cytosol: Aqueous(water) solution containing ions & various organic molecules.
Cytoskeleton: Protein-base framework of filamentous structures help maintain proper cell
shape & plays key roles in cell division & chromosome segregation from cell-generation to next
• ONCE thought to be specific to eukaryotes. Prokaryotes have it too. BIO 1000 Notes
• Prokaryotic ones = create & maintain proper shape of cells in cell division & for certain
bacteria, determining polarity of cells.
Two Types of Cells:
• Prokaryotic & eukaryotic. Prokaryote not used anymore as bacteria & archaea are
• Prokaryotic still used = refers to particular cell architecture, ONE LACKING A
Nucleoid: DNA-containing central region of the cell (Has no boundary membrane seperating it
from cytoplasm. <